1. Field of the Invention
This invention relates to fluid driven motors and has particular reference to motors driven by combined pressurized air and vacuum or partial vacuum, or increased and decreased densities of air molecules.
2. Description of the Prior Art
Motors operated by compressed air or by an increase in the density of air molecules have been used heretofore in which case air under a pressure greater than that of atmospheric pressure is applied at appropriate times against one side of one or more drive pistons or their equivalents while the opposite side is subjected to normal atmospheric pressure to drive the motor. Other motors have been used in which air under atmospheric pressure is applied to one side of a piston or the like and the other side is subjected to air pressure below atmospheric pressure or a reduction in the density of air molecules to produce a net driving force.
On the other hand, attempts have been made to increase the efficiency of air driven motors, such as small windshield wiper motors or the like by subjecting a drive piston thereof, on one side, to air pressure greater than atmospheric pressure and, on the other side thereof, to a negative air pressure less than atmospheric pressure. The U.S. Pat. Nos. to Oishei 1,694,279 and O'Shei 2,345,213 disclose such motors. These motors have not proved satisfactory, however, because they derive motive power, at least partly, from suction or air pressure below atmospheric pressure which is developed in the intake manifold of an internal combustion engine in which the air pressure varies in accordance with certain operating conditions of the engine, such as varying load conditions. Therefore, such engines cannot produce constant power even though they were developed in an attempt to obtain such constant power. Also, such motors utilize relatively low air pressure or increase in air molecules and a low degree of vaccum or reduction of air molecules.